I upgraded my iMac to a 4TB SSD and have a couple of questions

[Mac Fly (film)]

Before: Late 2014 iMac with 3 TB fusion drive.

After: Late 2014 iMac with 4 TB SSD.

Before the upgrade the hard drive in the machine seemed to be functioning ok and showed up in Disk Utility as a 3 terabyte drive, which it is. I upgraded to SSD for the added speed.

Question 1: The removed 3 terabyte Seagate Barracuda I put into an external hard drive dock in my attempt to wipe the drive clean using Disk Utility. The drive is showing up as 891 gigabytes in size for some odd reason. Trying to wipe the drive doesn’t change this size. Hmm 🤔. I’d like to get this drive back to being the 3 terabyte drive it is.

Question 2: regarding the 4 terabyte SSD, if you were me, would you join it up with the onboard 128 GB SSD chip on the motherboard of this 2014 iMac to create a new SSD fusion drive, or would you simply leave the sole boot drive be this new 4 TB Samsung EVO?

 

[stradify]

The original internal ssd is getting long in the tooth so I wouldn't trust it long term also it's a
lot slower ssd in comparison to your new 4TB one.

 

[Juicy Box]

Question 1: The removed 3 terabyte Seagate Barracuda I put into an external hard drive dock in my attempt to wipe the drive clean using Disk Utility. The drive is showing up as 891 gigabytes in size for some odd reason. Trying to wipe the drive doesn’t change this size. Hmm 🤔. I’d like to get this drive back to being the 3 terabyte drive it is.

My inital thought was that there are bad sectors that the drive can no longer use. If this is the case, I wouldn't use the drive for anything important.

But I started thinking, did you defuse or split the fusion drive prior to doing the swap?

Question 2: regarding the 4 terabyte SSD, if you were me, would you join it up with the onboard 128 GB SSD chip on the motherboard of this 2014 iMac to create a new SSD fusion drive, or would you simply leave the sole boot drive be this new 4 TB Samsung EVO?

Given the age, and the fact that the OEM SSDs in the 2014 iMacs are PCIe2x2 and max speeds are not as fast as the 2015 and up iMacs, I would at least test the OEM SSD speeds by itself first, and compare the speeds to the new SATA SSD. If it is only a little bit higher, probably not worth the potential trouble. If the OEM SSD is still in pretty good shape, and the speeds are significantly higher, I would say go for it.

Use AmorphousDiskMark to test the speeds, it is in the Mac App Store, and tests random speeds as well as sequential (unlike BMDST which only does sequential).

Test both drives and compare.

 

[Mac Fly (film)]

My inital thought was that there are bad sectors that the drive can no longer use. If this is the case, I wouldn't use the drive for anything important.

But I started thinking, did you defuse or split the fusion drive prior to doing the swap?

Didn’t touch the drive. Just backed up all of my files onto an external drive and then dragged them to the trash on the iMac, powered down the machine, opened it up and swapped the hard drive out for an SSD. I don’t see how the drive would be bad when it worked fine and was 3 TB before I removed it from the machine. The iMac Finder would occasionally freeze now and then while I used it. It wasn’t clear to me which part of the fusion drive was the cause of this. Finder would unfreeze again after thirty or forth seconds. Certainly didn’t happen everyday, but it was frequently enough to see a pattern. This was another reason I upgraded to an SSD. May be worth mentioning. But I never saw the drive show up below 3 TB size before. That’s something new since I removed the drive.

 

[Juicy Box]

You should always split or Defuse the Fusion Drive prior to using the two drives independently from each other. This could cause boot issues, but I wonder if this is what is causing the messed up storage size.

 

[chown33]

The swapped-out hard drive was previously part of a fusion drive, according to your first post You won't be able to do anything with it until you erase that particular formatting, or fix the split fusion drive.

To erase the disk, you'll first need to tell Disk Utility to View All Devices:

View all devices or only volumes in Disk Utility on Mac

In Disk Utility on your Mac, change the view setting to display all devices or only volumes.

support.apple.com

After you've done that, the external disk should appear as a device ready to be formatted. I suggest posting a screenshot of what appears in Disk Utility at that point.


Here's more info on fusion drives, but it's more about how to recover than an explanation of how to erase it:

How to fix a split Fusion Drive - Apple Support

If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. Here's how to fix it.

support.apple.com

Personally, I wouldn't make another fusion drive at all. It's more complex and more prone to failures, and as that article illustrates, it can "split" and become unusable.

If the 128GB SSD actually benchmarks at least 2X faster than the new SSD, then it might be worthwhile to set it up as a separate non-fusion disk, and put only the OS on it. Then the new SSD would hold big things, like photo or video libraries. I doubt you'll find a 2X speed difference, though, but it never hurts to measure things.

 

[Mac Fly (film)]

After you've done that, the external disk should appear as a device ready to be formatted. I suggest posting a screenshot of what appears in Disk Utility at that point.

 

[Mac Fly (film)]

Use AmorphousDiskMark to test the speeds, it is in the Mac App Store, and tests random speeds as well as sequential (unlike BMDST which only does sequential).

Test both drives and compare.

Only one drive showed up in the app to do this test. Thew new 4 TB SSD. No other drives listed in the drop down:

 

[Fishrrman]

If I recall, the 3tb HDDs used in iMacs around 2014 were prone to failure, and Apple even had a recall on them for a while.

I'd take the drive to a PC, and see if Windows could "format it out" to the correct size.

If the drive won't behave on Windows (either) -- I'd toss it.

However... you may be able to format the drive to full capacity on Windows.
If you can, take it back to the Mac and THEN try to re-format it to a Mac format.

 

[DeltaMac]

Open your Terminal, and enter the command: diskutil list - then press enter.
You should see all devices that will be some kind of storage drive.
And, you would be looking for one that is about 3 TB, or close to that.
If you don't see anything about that 3TB drive: It's a spinning hard drive, so do you hear the drive running in the external enclosure?

 

[chrfr]

Before: Late 2014 iMac with 3 TB fusion drive.

After: Late 2014 iMac with 4 TB SSD.

Before the upgrade the hard drive in the machine seemed to be functioning ok and showed up in Disk Utility as a 3 terabyte drive, which it is. I upgraded to SSD for the added speed.

Question 1: The removed 3 terabyte Seagate Barracuda I put into an external hard drive dock in my attempt to wipe the drive clean using Disk Utility. The drive is showing up as 891 gigabytes in size for some odd reason. Trying to wipe the drive doesn’t change this size. Hmm 🤔. I’d like to get this drive back to being the 3 terabyte drive it is.

Question 2: regarding the 4 terabyte SSD, if you were me, would you join it up with the onboard 128 GB SSD chip on the motherboard of this 2014 iMac to create a new SSD fusion drive, or would you simply leave the sole boot drive be this new 4 TB Samsung EVO?

Your external disk enclosure likely doesn’t support larger disks. This was a problem with older USB enclosures. Sometimes there were firmware updates but given that many of the 3TB disks were faulty, I’d stop using it altogether.
Do not ”fuse” your old SSD with the new one. There’s nothing to be gained here, and your risk for data loss goes up.
To use the 128GB SSD you just need to reformat it. It’s currently formatted as part of the old Fusion Drive, which is why it isn't showing any volumes.

 

[chown33]

View attachment 2132341

The only drives shown are the 128GB SSD and the external 4TB SSD. Nothing at all appears for any other drive.

I think @DeltaMac's suggestion to use diskutil list in a Terminal window is a good next step. You can drag-select its output text in the Terminal window, then copy-and-paste into a post here. Or post another screenshot showing the Terminal output.

@chrfr also makes a good point. Some enclosures simply won't work with large-capacity drives. Can you identify the make and model of the enclosure? With that information, it may be possible to find specs for it.

 

[Mac Fly (film)]

Open your Terminal, and enter the command: diskutil list - then press enter.
You should see all devices that will be some kind of storage drive.
And, you would be looking for one that is about 3 TB, or close to that.
If you don't see anything about that 3TB drive: It's a spinning hard drive, so do you hear the drive running in the external enclosure?

This screenshot is how the drive is showing up (keep in mind before I removed the 3 TB drive from my iMac is was showing up as 3 TB):

 

[Mac Fly (film)]

Your external disk enclosure likely doesn’t support larger disks. This was a problem with older USB enclosures.

Ahh..... penny drops

To use the 128GB SSD you just need to reformat it. It’s currently formatted as part of the old Fusion Drive, which is why it isn't showing any volumes.

I figured, but thanks for confirming

 

[DeltaMac]

Yes, that's certainly the enclosure with a drive with more capacity than the enclosure will support.
And, the drive would likely work just fine if you put it back inside the iMac. (don't do that!)
3TB storage is useful, so it might be worth getting a new enclosure for that.

 

[Mac Fly (film)]

3TB storage is useful, so it might be worth getting a new enclosure for that.

Hmm. 3 TB Seagate Barracuda. Eight years old. Thanks for the tips

 

[jz0309]

Hmm. 3 TB Seagate Barracuda. Eight years old. Thanks for the tips

What are you trying to use that drive for? I wouldn’t even trust it for backup anymore honestly, you can get brand new 4TB external drives at <$100 nowadays…